Conjugates of a phospholipid and a drug for the treatment of inflammatory bowel disease

ABSTRACT

Conjugates of drugs suitable for use in the treatment of inflammatory bowel disease and phospholipids, and their use in the treatment of inflammatory bowel disease, are disclosed. The disclosed conjugates serve as targeted prodrugs which are suitable for oral administration, and which are capable of releasing the drug selectively at the diseased tissue upon activation by PLA 2 .

FIELD AND BACKGROUND OF THE INVENTION

The present invention, in some embodiments thereof, relates topharmacology and, more particularly, but not exclusively, to a novelmethodology for the treatment of inflammatory bowel diseases.

Inflammatory bowel disease, or IBD, is a collective term encompassingrelated, but distinct, chronic inflammatory disorders of thegastrointestinal tract, such as Crohn's disease, ulcerative colitis(UC), indeterminate colitis, microscopic colitis and collagenouscolitis, with Crohn's disease and ulcerative colitis being the mostcommon diseases. Ulcerative colitis is confined to the large intestine(colon) and rectum, and involves only the inner lining of the intestinalwall. Crohn's disease may affect any section of the gastrointestinaltract (e.g., mouth, esophagus, stomach, small intestine, largeintestine, rectum and anus) and may involve all layers of the intestinalwall. Both diseases, as well as other IBDs, are characterized byabdominal pain and cramping, diarrhea, rectal and/or intestinalbleeding, weight loss and fever. The symptoms of these diseases areusually progressive, and sufferers typically experience periods ofremission followed by severe flare-ups. Less frequent, but alsopossible, IBD symptoms reflect mucosal inflammation of other sections ofthe GI tract, such as duodenitis, jejunitis and proctitis.

The goal of IBD therapy is to reduce the extent and symptoms of theinflammation, rather than to actually cure the disease (Kesisoglou andZimmermann, 2005). Aminosalicylates and corticosteroids are thetraditional mainstays of IBD therapy. Immunomodulators (e.g.6-mercaptopurine, its prodrug azathioprine, tacrolimus), antibiotics,and biological response modulators (infliximab) are also commonly used.

The most commonly used medications to treat IBD are anti-inflammatorydrugs such as the salicylates. Preparations of salicylate are effectivein treating mild to moderate disease and can also decrease the frequencyof disease flares when the medications are taken on a prolonged basis.Examples of salicylates include sulfasalazine, olsalazine, andmesalamine. Particularly, sulfasalazine and related drugs having thebioactive 5-amino-salicylic acid (5-ASA) moiety are widely used tocontrol moderate IBD symptoms and to maintain remission. All of thesemedications are given orally in high doses for maximal therapeuticbenefit. However, treatments with these medications is typicallyaccompanied with adverse side effects such as nausea, dizziness, changesin blood chemistry (including anemia and leukopenia), skin rashes anddrug dependence.

Corticosteroids are more potent and faster-acting anti-inflammatorydrugs in the treatment of IBD, as compared with salicylates. Prednisone,for example, is a corticosteroid commonly used in the treatment ofsevere cases of IBD. Nevertheless, potentially serious side effectslimit the use of corticosteroids to patients with more severe disease.Side effects of corticosteroids usually occur upon long term use andinclude thinning of the bone and skin, infections, diabetes, musclewasting, rounding of faces, psychiatric disturbances, and, on rareoccasions, destruction of hip joints.

In cases where IBD patients do not respond to salicylates orcorticosteroids, medications that suppress the immune system, namelyimmunosuppressants, are used. Examples of immunosuppressants includeazathioprine and 6-mercaptopurine. However, as immunosuppressants mayrender the patient immuno-compromised and susceptible to other diseases,the use thereof in the treatment of IBD is not recommended.

IBD presents a challenging target for drug delivery (Klotz and Schwab,2005). Because the original disease pathogenesis and some of the majorpathological manifestations are confined to the GIT tissue, an idealdelivery strategy for IBD should result in an elevated concentration ofthe therapeutic entity in the diseased intestinal tissue with minimalsystemic exposure. For example, studies have shown that for5-aminosalicylic acid (5-ASA), the therapeutic effect in IBD is directlycorrelated with the drug concentration in the diseased intestinal mucosa(see, FIG. 1) (Frieri et al., 2000).

Current delivery strategies in the treatment of IBD are based on eithera delayed release formulation or a chemical modification of the drugmolecule. Delayed release of the drug is typically achieved with polymercoating. For instance, Asacol° is an Edugarit S-coated 5-ASA formulationin which 5-ASA is designed to be released at pH >7, which is found inthe ileum and further; Pentasa° is an ethylcellulose-coated 5-ASAformulation in which 5-ASA is continuously release over several hours.The chemical modification approach is focused mainly on increasingfirst-pass hepatic metabolism and thereby reducing systemic drug levels(e.g., budesonide), or linking the drug (mainly 5-ASA) to a carrier viaazo bond to reduce the absorption of the complex in the small intestineand thereby targeting the colon; in the colon, bacterial azo-reductasesare able to liberate the free drug from the complex, effectively leadingto colonic drug targeting (e.g. sulfasalazine, olsalazine andbalsalazide).

All these strategies, however, target a region of the intestine(typically the colon), and not the actual diseased tissue itself. Thisis disadvantageous with respect to drug therapy and patient care, as itessentially leads to a waste of significant portion of the administereddose, and to increased chances of side effects. Additionally, itexcludes the use of these drug products in cases where the inflammationis outside of the particular targeted region, e.g., the small intestinein CD patients.

PLA₂ (phospholipases A₂) represent a family of enzymes that catalyze thehydrolysis of the sn-2 fatty acyl bond of phospholipids (PL), toliberate a free fatty acid and a lysophospholipid (see, FIG. 2). Atleast 19 enzymes with PLA₂ activity have been identified to date; 10isozymes are secreted from cells (sPLA₂), and the others are cytosolicenzymes (cPLA₂), however, by definition, all of them hydrolyze the esterbond at the sn-2 position of PL (Murakami and Kudo, 2002; Touqui andAlaoui-El-Azher, 2001). It has been reported that sPLA₂ enzymes do notdemonstrate any specific fatty acid selectivity (Kurz and Scriba, 2000;Laye and Gill, 2003).

In the past decade, PLA₂ expression in the inflamed tissue of IBDpatients, both CD and UC, has been consistently reported to besignificantly elevated. In CD, significantly increased gene expressionof PLA₂ was found in both the small and the large intestinal mucosa withactive inflammation (Haapamaki et al., 1999a), as well as significantlyhigher PLA₂ mRNA levels and activity in ileal mucosa from CD patientsthan from controls (FIG. 3A) (Lilja et al., 1995). In the protein level,the mass concentration of group II PLA₂ protein was found to besignificantly higher in colonic mucosa of CD patients compared tocontrol (Haapamaki et al., 1998; Minami et al., 1994), and the increasedlevel was correlated with the degree of the inflammatory activity in theintestinal wall (Haapamaki et al., 1998). PLA₂ activity in CD patientswas measured as well, and was reported to be significantly higher (about5-folds) than that in control subjects, with an association to thedegree of inflammation (see, for example, FIG. 3B) (Minami et al.,1994). The situation was not different in UC; significantly increasedgene expression of PLA₂ was found in inflamed large intestinal mucosa ofUC patients compared to control, with an association between the PLA₂mRNA levels and the degree of inflammation (Haapamaki et al., 1997). Theconcentration of PLA₂ protein in the colonic mucosa of UC patients wasfound to be significantly higher compared with control (Haapamaki etal., 1999b; Minami et al., 1994), and increased activity in the diseasedtissue of UC patient was evident as well (FIG. 3C) (Minami et al., 1994;Peterson et al., 1996). Overall, these data clearly indicate that PLA₂levels are elevated in the diseased IBD tissue, and support the theorythat PLA₂ is involved in the local and generalized pathologicalprocesses of IBD, CD and UC.

The present inventors have previously disclosed an exploitation of theesterase enzyme phospholipase A₂ (PLA₂) to mechanistically target drugmolecules to diseased cells. Thus, the present inventors have designedand investigated a series of conjugates of a phospholipid and thenon-steroidal anti-inflammatory drug indomethacin and of a phospholipidand valproic acid, differing in the length of the carbonic linkerbetween the PL and the drug moiety (Dahan et al., 2007; Dahan et al.,2008).

WO 91/16920 discloses lipid derivatives of anti-inflammatory drugs,including aspirin, other salicylates and other non-steroidalanti-inflammatory drugs (NSAIDs), which serve as phospholipid prodrugsthat are activated by digestive enzymes such as phospholipase A2 andother phospholipases and lysophospholipases, so as to release the drugand provide a steady level of the drug in the bloodstream while reducingtoxicity. According to the teachings of WO 91/16920, the phospholipidprodrugs are useful in treating chronic inflammatory diseases such asrheumatoid arthritis and osteoarthritis.

WO 00/31083 discloses phospholipid derivatives of NSAIDs in which thedrug is covalently linked to a phospholipid moiety via a bridging group,and which release the NSAID upon enzymatic cleavage at the diseasessite. According to the teachings of WO 00/31083, the bridging group isdesigned to be sensitive to cleavage by phospholipases such as PLA2 thatare specifically elevated at the site of the disease.

Additional background art includes Dahan and Amidon, Am. J. Physiol.Gastrointest. Liver Physiol. 2009; Dahan et al., J. Control. Release,2007; Dahan et al., J. Control. Release, 2008. Dahan and Hoffman, DrugMetab. Dispos., 2007; Dahan and Hoffman, European Journal ofPharmaceutical Sciences, 2005; Dahan and Hoffman, European Journal ofPharmaceutical Sciences, 2006; Dahan and Hoffman, PharmaceuticalResearch., 2006; Dahan et al., Drug Metab. Dispos., 2009; and Dvir etal., CNS Drug Rev. 2007.

SUMMARY OF THE INVENTION

While the prior art teaches phospholipid derivatives ofanti-inflammatory drugs which are activated by phospholipases so as torelease the drug at the diseased site, the prior art fails to teachphospholipid derivatives that can serve as a targeted drug deliverysystem in the treatment of inflammatory bowel diseases (IBD).

The prior art further fails to teach a targeted drug delivery systemthat can deliver an active drug to the small intestine, for thetreatment of, for example, Crohn's disease in patients with lesions inthe small intestine.

The prior art further fails to teach a targeted drug delivery system forthe treatment of IBD, which is suitable to be administered as an oralliquid dosage form.

The commonly used drug products for treating IBDs commonly require highdaily doses, at least partially to ineffective targeting to the diseasedtissue.

The present inventors have now designed a novel methodology fortargeting IBD drugs to diseased tissues. This novel methodology enablesthe treatment of IBD patients with inflamed tissues at the smallintestine, and further enables the treatment of IBD patients whileutilizing lower daily doses and optionally liquid oral formulations,thus increasing patient's compliance.

According to an aspect of some embodiments of the present inventionthere is provided a method of treating an inflammatory bowel disease ina subject in need thereof, the method comprising orally administering tothe subject a therapeutically effective amount of a conjugate whichcomprises a drug useful in the treatment of the inflammatory boweldisease covalently linked to a phospholipid.

According to some embodiments of the invention, the conjugate isformulated as a liquid oral formulation.

According to an aspect of some embodiments of the present inventionthere is provided a use of a conjugate which comprises a drug useful inthe treatment of the inflammatory bowel disease covalently linked to aphospholipid in the manufacture of a medicament for treating theinflammatory bowel disease, the medicament being formulated for oraladministration.

According to some embodiments of the invention, the medicament isformulated as a liquid oral formulation.

According to an aspect of some embodiments of the present inventionthere is provided a conjugate comprising a drug useful in the treatmentof the inflammatory bowel disease being covalently linked to aphospholipid, the conjugate being identified for use in the treatment ofthe inflammatory bowel disease via oral administration of the conjugate.

According to some embodiments of the invention, the conjugate isformulated as a liquid oral formulation.

According to an aspect of some embodiments of the present inventionthere is provided a pharmaceutical composition comprising, as an activeingredient, a conjugate which comprises a drug useful in the treatmentof the inflammatory bowel disease covalently linked to a phospholipid,and a pharmaceutically acceptable carrier, the composition beingformulated for oral administration and is being packaged in a packagingmaterial and identified in print, in or on the packaging material, foruse in the treatment of the inflammatory bowel disease.

According to some embodiments of the invention, the composition is beingformulated as a liquid oral formulation.

According to an aspect of some embodiments of the present inventionthere is provided an oral liquid dosage form comprising a conjugatewhich comprises a drug useful in the treatment of the inflammatory boweldisease covalently linked to a phospholipid, and a pharmaceuticallyacceptable carrier.

According to some embodiments of the invention, the inflammatory bowldisease is selected from the group consisting of Crohn's disease andulcerative colitis.

According to some embodiments of the invention, the inflammatory bowldisease is manifested in the small intestine.

According to some embodiments of the invention, the drug useful in thetreatment of inflammatory bowel disease is selected from the groupconsisting of a salicylate, a corticosteroid, an immunomodulator, anantibiotic and a biological response modulator.

According to some embodiments of the invention, the drug useful in thetreatment of inflammatory bowel disease comprises 5-ASA.

According to some embodiments of the invention, the drug useful in thetreatment of inflammatory bowel disease is selected from the groupconsisting of a drug that comprises 5-ASA, tacrolimus and methotrexate.

According to some embodiments of the invention, the phospholipid is aphosphoglycerol.

According to some embodiments of the invention, the drug is linked toposition sn-2 of the phosphoglycerol.

According to some embodiments of the invention, the drug is linked tothe phospholipid directly.

According to some embodiments of the invention, the drug is linked tothe phospholipid via a bridging unit.

According to some embodiments of the invention, the bridging unitcomprises an alkylene being from 1 to 20 carbon atoms in length.

According to some embodiments of the invention, the alkylene is beingfrom 3 to 6 carbon atoms in length.

According to some embodiments of the invention, the conjugate has ageneral Formula:

wherein:

A is an alkylene chain being 3-30 carbon atoms in length;

X is the bridging unit or absent;

D is the drug suitable for use in the treatment of the inflammatorybowel disease; and

R is selected from the group consisting of —P(═O)(ORa)(ORb), phosphorylcholine, phosphoryl ethanolamine, phosphoryl serine, phosphorylcardiolipin, phosphoryl inositol, ethylphosphocholine,phosphorylmethanol, phosphorylethanol, phosphorylpropanol,phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.

According to some embodiments of the invention, the drug comprises5-ASA.

According to some embodiments of the invention, the drug is selectedfrom the group consisting of a drug that comprises 5-ASA, amercaptopurine such tacrolimus and methotrexate.

According to some embodiments of the invention, X is an alkylene chainbeing 3-6 carbon atoms in length.

According to some embodiments of the invention, wherein R is phosphorylcholine.

According to some embodiments of the invention, A is an alkylene chainbeing 15 or 17 carbon atoms in length.

According to an aspect of some embodiments of the present inventionthere is provided a process of preparing a conjugate which comprises aphospholipid having attached thereto a drug suitable for the treatmentof an inflammatory bowel disease, the process comprising covalentlycoupling the drug to a lysophospholipid.

According to an aspect of some embodiments of the present inventionthere is provided a conjugate comprising a phospholipid having attachedthereto 5-amino salicylic acid (5-ASA).

According to some embodiments of the invention, the conjugate has ageneral Formula:

wherein:

A is an alkylene chain being 3-30 carbon atoms in length;

X is a bridging unit or absent;

D is 5-ASA; and

R is selected from the group consisting of —P(═O)(ORa)(ORb), phosphorylcholine, phosphoryl ethanolamine, phosphoryl serine, phosphorylcardiolipin, phosphoryl inositol, ethylphosphocholine,phosphorylmethanol, phosphorylethanol, phosphorylpropanol,phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.

According to some embodiments of the invention, X is an alkylene chainbeing 3-6 carbon atoms in length.

According to some embodiments of the invention, R is phosphoryl choline.

According to some embodiments of the invention, A is an alkylene chainbeing 15 or 17 carbon atoms in length.

According to some embodiments of the invention, there is provided anoral liquid dosage form comprising the PL-5-ASA conjugate as describedherein.

Unless otherwise defined, all technical and/or scientific terms usedherein have the same meaning as commonly understood by one of ordinaryskill in the art to which the invention pertains. Although methods andmaterials similar or equivalent to those described herein can be used inthe practice or testing of embodiments of the invention, exemplarymethods and/or materials are described below. In case of conflict, thepatent specification, including definitions, will control. In addition,the materials, methods, and examples are illustrative only and are notintended to be necessarily limiting.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the invention are herein described, by way ofexample only, with reference to the accompanying drawings. With specificreference now to the drawings in detail, it is stressed that theparticulars shown are by way of example and for purposes of illustrativediscussion of embodiments of the invention. In this regard, thedescription taken with the drawings makes apparent to those skilled inthe art how embodiments of the invention may be practiced.

In the drawings:

In the drawings:

FIG. 1 (Background Art) is graph demonstrating a correlation between IBDmucosal tissue concentrations of 5-ASA and soluble interleukin 2receptor (sIL-2R) (Frieri et al 2000 Gut);

FIG. 2 (Background Art) illustrates the chemical structure of anexemplary phospholipid (the phosphoglycerol lecithin), with the arrowindicating PLA₂ site of action;

FIG. 3A (Background Art) presents a Northern blot analysis of group IIPLA₂ mRNA in ileal mucosa from four patients, two controls (a and b) andtwo CD patients (c and d) (Lilja et al 1995 Gut); and

FIGS. 3B and 3C (Background Art) present bar graphs showing PLA₂activity in the colonic mucosa of control and CD patients (FIG. 3B) andUC patient (FIG. 3C) (Minami et al 1994 Gu).

DESCRIPTION OF SPECIFIC EMBODIMENTS OF THE INVENTION

The present invention, in some embodiments thereof, relates topharmacology and, more particularly, but not exclusively, to a novelmethodology for the treatment of inflammatory bowel diseases.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not necessarily limited in itsapplication to the details set forth in the following description orexemplified by the Examples. The invention is capable of otherembodiments or of being practiced or carried out in various ways.

The methodology described herein is aimed at targeting the drug ofinterest to the diseased tissue per se, in order to improve drug therapyand patient care in IBD, as is detailed hereinbelow.

Based on the findings that PLA₂ is overexpressed in the GIT of patientssuffering from IBDs, the present inventors have realized that previouslydescribed phospholipid derivatives of anti-inflammatory drugs, whenadministered orally to IBD patients, would release the drug in the GIT,rather than in the blood system. The present inventors have furtherrealized that the overexpression of PLA₂ in the GIT of patientssuffering from IBDs can be exploited for targeted delivery ofanti-inflammatory drugs for treating the IBD.

The present inventors have thus realized that conjugates of aphospholipid and an IBD drug (also referred to herein, interchangeably,as PL-drug conjugates) can be designed and utilized so as to improvetherapeutic index and patient care in IBD, based of the followingunderlying basis.

Since the activation of a PL-drug conjugate as disclosed herein isPLA₂-mediated, the increased levels of this enzyme in the diseasedtissue leads to increased free drug in the actual diseased tissues,essentially accompanied by decreased drug levels in non-diseasedtissues, resulting in extended therapeutic index and improved drugtherapy. In fact, it has been realized that the use of conjugates of aphospholipid and an IBD drug provides a “sink effect” since theconjugate acts as a prodrug which is continuously targeted to thediseased tissue and is continuously released in the diseased tissue, asa result of the overexpression of PLA₂. Since no accumulation of theprodrug is effected at the diseased tissue, systemic absorption of thedrug is reduced, and thus, adverse side effects are reduced. Inaddition, the amount of free drug at the diseased tissue is increased,and overall, the therapeutic index (efficacy vs. toxicity) is improved.

Notably, the prodrug is targeted to diseased tissues and not to adiseased site, where both diseased and healthy tissues are present, thusavoiding adverse side effects.

It is to be noted that at least some of the currently available IBD drugproducts are utilized in very high daily oral doses, at least partiallydue to the poor targeting of the available formulations. Productscontaining 5-ASA, for example, represent some of the highest oraldose/day medications on the market, with a maximum daily dose of up to4.8 grams, which sometimes correspond to eight tablets and even more.The targeted delivery of the drug to the inflamed tissue by thedisclosed conjugates thus decreases the required dose, leading toimproved convenience and better patient compliance.

In addition, unlike the currently available IBD drug products, theconjugates described herein enable specific delivery to diseased tissuethroughout the entire gastrointestinal tract (GIT), including the smallintestine. It is to be noted that currently available IBD drug products,and 5-ASA products in particular, deliver the drug to the colon, andhence are not effective in treating patients having inflammatory lesionsin other tissues, and particularly in small intestine tissues. This isparticularly advantageous in the treatment of Crohn's disease patientsthat have such lesions, and for which current drug therapies areineffective.

The use of the conjugates described herein further provides for targetedrelease of the drug without formulation manipulations and hence enablesto utilize liquid formulations instead of solid dosage forms (asdescribed hereinabove in the context of formulation manipulations madein order to achieve targeted delivery to certain areas in the GIT).Since the targeting methodology described herein is notformulation-dependent but integral to the PL-drug conjugate molecule, itis possible to formulate it in a liquid oral dosage form withoutaffecting the targeting abilities. This is of great benefit in, forexample, pediatric and elderly populations, for whom swallowing of asolid dosage form is impossible/painful. This advantage becomes evenmore important in light of the large size of most of oral IBD productsavailable on the market.

Finally, the methodology disclosed herein is drug-independent, as itdepends on the conjugation to a phospholipid. Thus, any drug of interestfor the treatment of IBD can be utilized and is encompassed by theembodiments of the present invention.

Embodiments of the present invention thus pertain to a novel use of aconjugate of a phospholipid and an IBD drug (PL-drug conjugates), asdescribed herein. While some of the PL-drug conjugates have beenpreviously described in the art, none was described in the context ofthe methodologies described herein. Embodiments of the present inventionalso relate to those conjugates of a phospholipid and an IBD drug, whichhave not been previously described, including, but not limited to, aconjugate of a phospholipid (e.g., a glycerophosphate) and an IBD drugthat comprises or consists of 5-ASA, a conjugate of a phospholipid(e.g., a glycerophosphate) and a mercaptopurine such tacrolimus, and aconjugate of a phospholipid (e.g., a glycerophosphate) and methotrexate,each further comprising, optionally, a bridging unit, as describedherein.

For any of the aspects of embodiments of the present invention, thereare provided conjugates, each comprising a drug useful in the treatmentof the inflammatory bowel disease being covalently linked to aphospholipid.

As used herein, the phrase “a drug useful in the treatment of aninflammatory bowel disease”, which is also referred to hereininterchangeably as “a drug useful in the treatment of an IBD” or as “anIBD drug”, or simply as “drug”, encompasses any drug that has atherapeutic effect on an inflammatory bowl disease, as the latter isdefined herein. This phrase encompasses commercially available drugs, aswell as drugs that are under development or that has been suggested asuseful in the treatment of an IBD. This phrase further encompasses anypharmaceutically acceptable salt of these drugs, known prodrugs of thesedrugs, and derivatives of these drugs, and any crystalline form of thesedrugs (including amorphous form), as these terms are defined herein, allof which are such that exhibit a therapeutic effect on an IBD.

Representative examples of IBD drugs include, but are not limited,salicylates (e.g., aminosalicylates such as drugs comprising5-amino-salicylic acid (5-ASA), for example, sulfasalazine, olsalazine,and mesalamine); a cortocisteroid (e.g., Prednisone); an immunomodulator(e.g., 6-mercaptopurine, its prodrug azathioprine, tacrolimus); anantiobiotic; and a biological response modulator (e.g., infliximab); aswell as some anti-cancer agents (e.g., paclitaxel, methotrexate andcyclosporine).

Exemplary drugs include, but are not limited to, 5-ASA, methotrexate,paclitaxel, tacrolimus, colchicine, cyclosporine, Azathioprine,mercaptopurine, Beclomethasone Dipropionate, Infliximab, Traficet-EN,and any other drug for treating an inflammatory bowel disease which iscommercially available or is currently under research.

According to some embodiments of the invention, the drug useful in thetreatment of inflammatory bowel disease comprises 5-ASA.

By “a drug that comprises 5-ASA” are encompassed 5-ASA itself (e.g.,mezalazine) and compounds that are metabolized to release 5-ASA (e.g.,sulfasalazine).

Exemplary drugs that comprise 5-ASA include, but are not limited to,mezalazine, sulfasalazine, olsalazine and balsalazide.

As discussed hereinabove 5-ASA is the mainstay of treatment in IBD.Further, since a correlation has been found between the 5-ASA levels inthe inflamed tissue and the therapeutic effect of the drug (see, FIG.1), an augmented efficacy, as exhibited by the disclosed conjugates, isparticularly beneficial.

According to some embodiments of the invention, the drug useful in thetreatment of inflammatory bowel disease is methotrextae.

According to some embodiments of the invention, the drug useful in thetreatment of inflammatory bowel disease is a mercatopurine such as, forexample, tacrolimus.

As used herein, a “phospholipid” describes compounds that comprise alipid moiety and a phosphate moiety. Commonly available phospholipidsare those belonging to the glycerophospholipid class (also known asphosphoglycerols or as diacylglyceride phosphates), including, but notlimited to, phosphatidic acid (phosphatidate) (PA),phosphatidylethanolamine (cephalin) (PE), phosphatidylcholine (lecithin)(PC), phosphatidylserine (PS), and phosphoinositides such as, forexample, phosphatidylinositol (PI), phosphatidylinositol phosphate(PIP), phosphatidylinositol bisphosphate (PIP2) and phosphatidylinositoltriphosphate (PIPS); and those belonging to the phosphosphingolipidsclass (which are derived from sphongosine), including, but not limitedto, ceramide phosphorylcholine (sphingomyelin) (SPH), ceramidephosphorylethanolamine (Cer-PE), and ceramide phosphorylglycerol.

Phosphoglycerols have a glycerolic backbone to which are attached twofatty acyl groups at positions sn-1 and sn-2, and one phosphate moietyat position sn-3.

Phosphosphingolipids have a sphingosine backbone which comprises oneunsaturated fatty acyl, and to which are attached one fatty acyl via anamide bond and one phosphate moiety.

According to some embodiments of the invention, the phospholipid isphosphoglycerol.

According to some embodiments of the invention, the drug is linked toposition sn-2 of the phosphoglycerol. Such phospholipids are efficientsubstrates of PLA₂.

In some embodiments, the IBD drug is linked to an availablephosphglycerol (e.g., lechitin, lysolechitin, phsophinositol, and thelike) by replacing the fatty acyl or acyl at position sn-2 of thephosphoglycerol by the drug moiety.

In these embodiments, the phospholipid portion of the conjugatecomprises a fatty acyl as present in the phosphoglycerol prior toconjugation, preferably at position sn-1, and a phosphate moiety aspresent in the phosphglycerol prior to conjugation, at position sn-3.

The term “acyl” as used herein describes a —C(═O)—R moiety, typicallyderived from the corresponding carboxylate (R′—O—C(═O)—R). The term“fatty acyl” as used herein describes an acyl derived from fatty acid,such that R is a high hydrocarbon chain, typically being at least 2 orat least 3 carbon atoms in length, or from 6 to 30 carbon atoms inlength. The hydrocarbon chain can be saturated or unsaturated, thelatter can comprise one or more double and/or triple bonds.

In some embodiments, the hydrocarbon chain in a fatty acyl comprises anodd number of carbon atoms, thus being derived from a fatty acid.

Representative examples of fatty acyls are those which comprise ahydrocarbon chain that is derived from palmitic acid, and as such are 15carbon atoms in length, or from stearic acid, and as such are of 17carbon atoms in length.

In some embodiments, the drug is linked to the phospholipid via an esterbond.

As used herein, an “ester bond” describes a —O—C(═O)— bond, which istypically formed by reacting a hydroxyl group and a carboxylate orcarbonyl group.

In some embodiments, the conjugate comprises a phospholipid that isderived from a glycerophospholipid (a phosphoglycerol), as describedherein, in which the IBD drug is attached at position sn-2 of theglycerolic backbone via an ester bond (replacing a fatty acyl of thephosphoglycerol at that position), whereby the other fatty acyl, atposition sn-1, and the phosphate moiety at position sn-3 are the same asin the phosphoglycerol.

According to some embodiments of the invention, the IBD drug is linkedto the phospholipid directly.

In some embodiments, the IBD drug is linked to the phospholipiddirectly, via an ester bond, as defined herein. Such conjugates aretypically formed by utilizing IBD drugs that have a carboxylate group(e.g., a carboxylic acid group) or by utilizing derivatives of IBD drugswhich have been modified to include a carboxylate group or any otherreactive group that can form a bond with the hydroxyl group of thephospholipid (see, Example 1 hereinbelow).

According to some embodiments of the invention, the drug is linked tothe phospholipid via a bridging unit.

As used herein, a “bridging unit”, which is also referred to hereininterchangeably as a linking unit, a linking moiety or simply as alinker, is a moiety that is attached to the phospholipid at one endthereof and to the IBD drug at another end thereof, and thus links theIBD drug to the phospholipid.

The bridging unit is typically derived from a suitable precursor,namely, a bifunctional compound that has a first and a second reactivegroup, as described in detail in Example 1 in the Examples section thatfollows.

In some embodiments, the bridging unit is desired in cases where the IBDdrug utilized does not have a functional group that can form a covalentbond (e.g., an ester bond) with the phospholipid. In these embodiments,the bridging unit can be seen as providing a chemical functionality forattaching the IBD drug to the phospholipid.

In some embodiments, the bridging unit is desired for obviating sterichindrance of the ester bond that is to be subjected to enzymatichydrolysis (e.g., by PLA₂).

Thus, in some embodiments, the desired length of the bridging unitdepends, in part, on the size of the linked drug, such that, forexample, for bulky drugs, relatively long (e.g. higher than 2 and evenhigher than 6 carbon atoms) moieties are desired, whereby for relativelysmall drug molecules, moieties being of 2-6 or from 3-5 carbon atoms inlength suffice.

In some embodiments, the bridging unit is 1 carbon atom, 2 carbon atoms,3 carbon atoms, 4 carbon atoms, 5 carbon atoms, 6 carbon atoms inlength, and can be even of 30 carbon atoms or more, in length.

Exemplary bridging units include, but are not limited to, hydrocarbonsbeing from 1 to 30 carbon atoms in length, optionally interrupted by oneor more heteroatoms; amino acids; and/or peptides (e.g., short peptidesbeing of 2-10 amino acids).

As used herein, the term “hydrocarbon” encompasses any moiety thatcomprises carbons and hydrogens covalently linked, in a form of anyoneor a combination of alkyl, alkenyl, cycloalkyl, alkynyl and aryl, suchthat a backbone chain linking the IBD drug to the phospholipid is from 1to 30 carbon atoms in length, or from 1 to 20, or from 1 to 15, or from2 to 20, or from 2 to 15, or from 3 to 30, or from 3 to 20, or from 3 to15, or from 2 to 10, or from 3 to 10, or from 3 to 6, or from 3 to 5,carbon atoms in length.

According to some embodiments of the invention, the bridging unitcomprises an alkylene being from 1 to 20 carbon atoms in length, or from2 to 20 carbon atoms in length, or from 3 to 20 carbon atoms in length,or from 3 to 10 carbon atoms in length, or from 3 to 6, or from 3 to 5carbon atoms in length.

As used herein, the term “alkylene” describes a hydrocarbon that iscomprised of an alkyl chain, which can be represented by —(CRcRd)_(n)-,wherein Rc and Rd can be the same or different in any unit of the nunits in the chain, and each can independently be hydrogen or any of thesubstituents described herein for an “alkyl”.

Alternatively, the bridging unit comprises or is derived from an aminoacid or a short peptide (e.g., di- or tri-peptides).

Any of the naturally occurring or non-naturally occurring amino acids,and peptides made therefrom, are contemplated.

In some embodiments, the bridging unit is selected such that uponenzymatic cleavage of the bond connecting it to the phospholipid, thereleased moiety, which contains the IBD drug, can exert its therapeuticeffect.

In some embodiments, the released moiety is the IBD drug having thebridging unit attached thereto (whereby the bridging unit terminateswith a functional group generated by the cleavage), and such a moiety iscapable of exerting a therapeutic effect comparable to that of the IBDdrug per se (namely, the bridging unit does not interfere with thetherapeutic activity of the IBD drug).

In some embodiments, the released moiety is the IBD drug having thebridging unit attached thereto (whereby the bridging unit terminateswith a functional group generated by the cleavage), and such a moiety iscapable of undergoing cleavage under physiological conditions (e.g., apH-dependent cleavage or an enzymatic cleavage by e.g., esterases,amidases or proteolytic enzymes), so as to release the IBD drug.

In some embodiments, the released moiety is the IBD drug having thebridging unit attached thereto (whereby the bridging unit terminateswith a functional group generated by the cleavage), and such a moiety iscapable of undergoing self-immolation under physiological conditions asdescribed supra, to thereby release the IBD drug.

In some embodiments, the bridging moiety is selected such that uponrelease of the IBD drug, by cleavage or self-immolation of the IBD drughaving the bridging unit attached thereto (whereby the bridging unitterminates with a functional group generated by the cleavage), abiocompatible moiety is formed (e.g., a metabolite such as, for example,an amino acid or a peptide, urea, and the like).

The PL-drug conjugates described herein can be collectively representedby the following general Formula:

wherein:

A is saturated or unsaturated, substituted or unsubstituted hydrocarbonchain being 2-30 carbon atoms in length;

X is a bridging unit, as described herein, or absent;

D is the drug suitable for use in the treatment of said inflammatorybowel disease (an IBD drug), as described herein; and

R is selected from the group consisting of —P(═O)(ORa)(ORb), phosphorylcholine, phosphoryl ethanolamine, phosphoryl serine, phosphorylcardiolipin, phosphoryl inositol, ethylphosphocholine,phosphorylmethanol, phosphorylethanol, phosphorylpropanol,phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.

In some embodiments, D is a drug that comprises 5-ASA, as definedherein.

In some embodiments, D is a mercaptopurine such as tacrolimus.

In some embodiments, D is methotrexate.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, and R is selected from the groupconsisting of phosphate, phosphoryl choline, phosphoryl serine,phosphoryl enthanolamine, and a phosphoryl inositol.

In some of these embodiments, X can be absent or can be an alkylene offrom 3 to 6 carbon atoms.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, R is selected from the groupconsisting of phosphate, phosphoryl choline, phosphoryl serine,phosphoryl enthanolamine, and a phosphoryl inositol, and D is a drugthat comprises 5-ASA, as defined herein.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, R is selected from the groupconsisting of phosphate, phosphoryl choline, phosphoryl serine,phosphoryl enthanolamine, and a phosphoryl inositol, and D is amercaptopurine such as tacrolimus.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, R is selected from the groupconsisting of phosphate, phosphoryl choline, phosphoryl serine,phosphoryl enthanolamine, and a phosphoryl inositol, and D ismethotrexate.

In some of these embodiments, X can be absent or can be an alkylene offrom 3 to 6 carbon atoms.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, and D is a drug that comprises5-ASA, as defined herein.

In some of these embodiments, X can be absent or can be an alkylene offrom 3 to 6 carbon atoms.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, and D is a mercaptopurine such astacrolimus.

In some of these embodiments, X can be absent or can be an alkylene offrom 3 to 6 carbon atoms.

In some embodiments, A is a hydrocarbon chain derived from a fatty acid,as defined herein for a fatty acyl, and D is methotrexate.

In some of these embodiments, X can be absent or can be an alkylene offrom 3 to 6 carbon atoms.

According to some embodiments, there is provided a conjugate thatcomprises a drug that comprises 5-ASA as defined herein, beingcovalently linked to a phospholipid, as defined herein.

In some of these embodiments, the drug is attached to the phospholipidas defined herein, either directly, or via a bridging unit, as definedherein.

According to some embodiments, there is provided a conjugate thatcomprises any of the IBD drugs as defined herein, being covalentlylinked to a phospholipid, as defined herein.

In some of these embodiments, the drug is attached to the phospholipidas defined herein, either directly, or via a bridging unit, as definedherein.

In some embodiments, the drug is a mercaptopurine such as tacrolimus.

In some embodiments, the drug is methotrexate.

According to an aspect of some embodiments of the present inventionthere is provided a process of preparing a conjugate which comprises aphospholipid having attached thereto a drug suitable for the treatmentof an inflammatory bowel disease, essentially as described herein. Theprocess is effected by covalently coupling that drug to thephospholipid. In some embodiments, the process is effected by firstcoupling to the phospholipid a precursor compound for generating thebridging moiety, and then coupling to the obtained phospholipid, havingthis precursor compound coupled thereto, the IBD drug. Further detailsregarding the process, according to these embodiments, are describedunder Example 1 in the Examples section that follows.

In any of the embodiments and aspects of the present invention, thePL-drug conjugate can also be in a form of a pharmaceutically acceptablesalt thereof, a hydrate or a solvate thereof, and be in any crystallineform, including an amorphous form.

The term “solvate” refers to a complex of variable stoichiometry (e.g.,di-, tri-, tetra-, penta-, hexa-, and so on), which is formed by asolute (the conjugate as described herein) and a solvent, whereby thesolvent does not interfere with the biological activity of the solute.Suitable solvents include, for example, ethanol, acetic acid and thelike.

The term “hydrate” refers to a solvate, as defined hereinabove, wherethe solvent is water or an aqueous solution.

The phrase “pharmaceutically acceptable salt” refers to a chargedspecies of the parent compound and its counter ion, which is typicallyused to modify the solubility characteristics of the parent compoundand/or to reduce any significant irritation to an organism by the parentcompound, while not abrogating the biological activity and properties ofthe administered compound. An example, without limitation, of apharmaceutically acceptable salt would be a hydroxyl anion (O⁻) and acation such as, but not limited to, ammonium, sodium, potassium and thelike. Another example, without limitation, of a pharmaceuticallyacceptable salt would be an ammonium cation and an acid addition saltthereof. Examples of acid addition salts include, but are not limitedto, hydrochloric acid addition salt, sulfuric acid addition salt(sulfate salt), acetic acid addition salt, ascorbic acid addition salt,benzenesulfonic acid addition salt, camphorsulfonic acid addition salt,citric acid addition salt, maleic acid addition salt, methanesulfonicacid addition salt, naphthalenesulfonic acid addition salt, oxalic acidaddition salt, phosphoric acid addition salt, succinic acid additionsalt, sulfuric acid addition salt, tartaric acid addition salt, andtoluenesulfonic acid addition salt.

The conjugates described herein can be seen as a prodrug. As used in theart, the term “prodrug” refers to an agent, which is converted into theactive compound (the active drug) in vivo. Prodrugs are typically usefulfor facilitating the administration of the parent drug. In embodimentsof the present invention, the conjugate serves as a targeted prodrug,which releases the active drug at a selected tissue (e.g., an inflamedtissue in the GI tract).

As discussed hereinabove, the PL-drug conjugates as described herein canbe advantageously utilized in the treatment of an inflammatory boweldisease.

According to an aspect of some embodiments of the present inventionthere is provided a method of treating an inflammatory bowel disease ina subject in need thereof, the method comprising administering to thesubject a therapeutically effective amount of a conjugate whichcomprises a drug useful in the treatment of the inflammatory boweldisease covalently linked to a phospholipid, as described herein.According to some embodiments of the present invention, administeringthe described conjugate is effected orally. According to someembodiments of the invention, the conjugate is utilized as apharmaceutical composition that comprises the conjugate and optionallyfurther comprises a pharmaceutical acceptable carrier, as describedherein.

According to an aspect of some embodiments of the present inventionthere is provided a use of a conjugate which comprises a drug useful inthe treatment of the inflammatory bowel disease covalently linked to aphospholipid in the manufacture of a medicament for treating saidinflammatory bowel disease. According to some embodiments of the presentinvention, the medicament is formulated for oral administration.According to some embodiments of the invention, the conjugate isutilized as a pharmaceutical composition that comprises the conjugateand optionally further comprises a pharmaceutical acceptable carrier, asdescribed herein.

According to an aspect of some embodiments of the present inventionthere is provided a conjugate which comprises a drug useful in thetreatment of the inflammatory bowel disease being covalently linked to aphospholipid, and which is identified for use in the treatment of theinflammatory bowel disease. In some embodiments, the conjugate isidentified for use via oral administration of the conjugate. Accordingto some embodiments of the invention, the conjugate is utilized as apharmaceutical composition that comprises the conjugate and optionallyfurther comprises a pharmaceutical acceptable carrier, as describedherein.

According to an aspect of some embodiments of the present inventionthere is provided a pharmaceutical composition comprising, as an activeingredient, a conjugate which comprises a drug useful in the treatmentof the inflammatory bowel disease covalently linked to a phospholipid,and a pharmaceutically acceptable carrier. According to some embodimentsof the present invention, the composition is formulated for oraladministration. According to some embodiments of the present invention,the pharmaceutical composition is packaged in a packaging material andidentified in print, in or on said packaging material, for use in thetreatment of said inflammatory bowel disease.

As used herein, the phrase “inflammatory bowel disease (IBD)” refers toa disorder or disease characterized by inflammatory activity in the GItract. Examples of IBDs include, without limitation, Crohn's disease(both distal and proximal), ulcerative colitis, indeterminate colitis,microscopic colitis, collagenous colitis, idiopathic inflammation of thesmall and/or proximal intestine, irritant bowel syndrome, andIBD-related diarrhea.

In some embodiments, the IBD is manifested in the small intestine. By“manifested in the small intestine” it is meant that at least a portionof the inflamed tissues in the diseased subject are found in the smallintestine.

IBDs that can be manifested in the small intestine include, but are notlimited to, Crohn's disease and ulcerative colitis.

In some embodiments, the IBD is Crohn's disease. It is to be noted thatwhile IBDs such as, for example, colitis, typically involve inflammationin the large intestine (colon) and/or the ileum, Crohn's disease ofteninvolves inflammation in certain regions of the small intestine.Targeting the small intestine is a difficult task to achieve, asdescribed in detail hereinabove and to date, none of the currentlyavailable IBD drug therapies can target the small intestine.

In some embodiments, the IBD is associated with overexpression of PLA₂at an inflamed tissue of the GI tract.

In some embodiments, the inflamed tissue is in the small intestine.

It is to be noted that since, in some embodiments, the PL-drugconjugates disclosed herein are designed to release the drug at aninflamed tissue in the GI tract which is associated with overexpressionof PLA₂, the conjugate of choice can comprise any IBD drug that issuitable for treating the inflammation at this inflamed tissue.

As discussed hereinabove, the conjugates described herein arecharacterized by an improved therapeutic index, at least compared withthe IBD drug when used in a non-conjugated form.

As used herein and known in the art, a “therapeutic index” describes theratio between the toxic dose of a drug and the therapeutic dose of thedrug. This ratio is often defined as LD₅₀:ED₅₀. A desirabletherapeutically active agent would have an ED₅₀ value much higher thatthe LD₅₀ value.

The “sink” effect and other effects exhibited by the disclosedconjugates, as discussed supra provide for an improved efficacy and areduced toxicity (reduced adverse side effected) of the drug.

In some embodiments, the conjugates described herein are characterizedby a therapeutic index that is significantly improved, e.g., improved byat least 10%, or by at least 50%, or even by 100%, as compared to theIBD drug product in which the drug is utilized as a non-conjugated form.

In any of the aspects described herein in the context of treatment of anIBD, the conjugates are utilized in an amount effective to achieve theintended purpose, namely, in a therapeutically effective amount. Atherapeutically effective amount means an amount of compounds presentedherein effective to prevent, alleviate or ameliorate symptoms of thedisorder, or prolong the survival of the subject being treated.

Determination of a therapeutically effective amount is well within thecapability of those skilled in the art, especially in light of thedetailed disclosure provided herein.

For any of the conjugates as presented herein, the therapeuticallyeffective amount or dose can be estimated initially from activity assaysin animals. Such information can be used to more accurately determineuseful doses in humans.

Toxicity and therapeutic efficacy of the compounds presented herein canbe determined by standard pharmaceutical procedures in experimentalanimals, e.g., by determining the EC₅₀ (the concentration of a compoundwhere 50% of its maximal effect is observed) and the LD₅₀ (lethal dosecausing death in 50% of the tested animals) for a subject compound. Thedata obtained from these activity assays and animal studies can be usedin formulating a range of dosage for use in human.

Dosage amount and interval may be adjusted individually to provideplasma levels of the compounds presented herein which are sufficient tomaintain the desired effects, termed the minimal effective concentration(MEC). The MEC will vary for each preparation, but can be estimated fromactivity data; e.g., the concentration of the conjugates necessary toachieve 50-90% remission of an inflamed tissue. Dosages necessary toachieve the MEC will depend on individual characteristics and route ofadministration. HPLC assays or bioassays can be used to determine plasmaconcentrations.

Dosage intervals can also be determined using the MEC value.Preparations should be administered using a regimen, which maintainsplasma levels above the MEC for 10-90% of the time, preferable between30-90% and most preferably 50-90%.

Depending on the severity and responsiveness of the condition to betreated, dosing can also be a single or chronic periodic administration,with course of periodic treatment lasting from several days to severalweeks or until sufficient amelioration is effected during the periodictreatment or substantial diminution of the disorder state is achievedfor the periodic treatment.

The amount of a composition to be administered will, of course, bedependent on the subject being treated, the severity of the affliction,the manner of administration, the judgment of the prescribing physician,etc.

In some embodiments, the “sink” effect and other effects exhibited bythe disclosed conjugates, as discussed supra, enables to use lower dailydoses of the conjugate, as compared to a non-conjugated IBD drugproduct.

In some embodiments, a therapeutically effective amount of the conjugatedescribed herein is lower by at least 10%, at least 20%, at least 30% atleast 40% and even by 50%, compared to a corresponding IBD in anon-conjugates form.

A therapeutically effective amount of the conjugate described herein canrange from 0.1 to 100 mg/kg body/day, including any value within thisrange. As noted hereinabove, the conjugates described herein areadvantageously utilized as oral formulations.

For oral administration, the conjugate or a pharmaceutical compositionor a medicament containing same can be formulated readily by combiningthe conjugate with pharmaceutically acceptable carriers well known inthe art. Such carriers enable the conjugate to be formulated as tablets,pills, dragees, capsules, liquids, gels, syrups, slurries, suspensions,and the like, for oral ingestion by a patient.

Hereinafter, the term “pharmaceutically acceptable carrier” refers to acarrier or a diluent that does not cause significant irritation to anorganism and does not abrogate the biological activity and properties ofthe administered compound. Examples, without limitations, of carriersare: propylene glycol, saline, emulsions and mixtures of organicsolvents with water, as well as solid (e.g., powdered) and gaseouscarriers.

Herein the term “excipient” refers to an inert substance added to apharmaceutical composition to further facilitate administration of acompound. Examples, without limitation, of excipients include calciumcarbonate, calcium phosphate, various sugars and types of starch,cellulose derivatives, gelatin, vegetable oils and polyethylene glycols.

Techniques for formulation and administration of drugs may be found in“Remington's Pharmaceutical Sciences” Mack Publishing Co., Easton, Pa.,latest edition, which is incorporated herein by reference.

Pharmaceutical compositions of the present invention may be manufacturedby processes well known in the art, e.g., by means of conventionalmixing, dissolving, granulating, dragee-making, levigating, emulsifying,encapsulating, entrapping or lyophilizing processes.

Pharmaceutical compositions for use in accordance with the presentinvention thus may be formulated in conventional manner using one ormore pharmaceutically acceptable carriers comprising excipients andauxiliaries, which facilitate processing of the compounds presentedherein into preparations which, can be used pharmaceutically. Properformulation is dependent upon the route of administration chosen.

Pharmacological preparations for oral use can be made using a solidexcipient, optionally grinding the resulting mixture, and processing themixture of granules, after adding suitable auxiliaries if desired, toobtain tablets or dragee cores. Suitable excipients are, in particular,fillers such as sugars, including lactose, sucrose, mannitol, orsorbitol; cellulose preparations such as, for example, maize starch,wheat starch, rice starch, potato starch, gelatin, gum tragacanth,methyl cellulose, hydroxypropylmethyl-cellulose, sodiumcarbomethylcellulose; and/or physiologically acceptable polymers such aspolyvinylpyrrolidone (PVP). If desired, disintegrating agents may beadded, such as cross-linked polyvinyl pyrrolidone, agar, or alginic acidor a salt thereof such as sodium alginate.

Dragee cores are provided with suitable coatings. For this purpose,concentrated sugar solutions may be used which may optionally containgum arabic, talc, polyvinyl pyrrolidone, carbopol gel, polyethyleneglycol, titanium dioxide, lacquer solutions and suitable organicsolvents or solvent mixtures. Dyestuffs or pigments may be added to thetablets or dragee coatings for identification or to characterizedifferent combinations of active compound doses.

Pharmaceutical compositions which can be used orally, include push-fitcapsules made of gelatin as well as soft, sealed capsules made ofgelatin and a plasticizer, such as glycerol or sorbitol. The push-fitcapsules may contain the active ingredients in admixture with fillersuch as lactose, binders such as starches, lubricants such as talc ormagnesium stearate and, optionally, stabilizers. In soft capsules, theactive ingredients may be dissolved or suspended in suitable liquids,such as fatty oils, liquid paraffin, or liquid polyethylene glycols. Inaddition, stabilizers may be added. All formulations for oraladministration should be in dosages suitable for the chosen route ofadministration.

In some embodiments, the conjugate or the composition or medicamentcontaining same are formulated as a liquid formulation for oraladministration.

The phrase “liquid formulation for oral administration” is also referredto herein interchangeably as “an oral liquid formulation” or as an “anoral liquid dosage form” and describes a formulation of the conjugate asdescribed herein which is in a liquid form and which can be administeredby swallowing the liquid.

By “liquid form” it is meant that a substantial portion of theformulation is liquid. This expression encompasses a solution, in whichthe conjugate is dissolved or solubilized, a dispersion or suspension ofsmall particles of the conjugate within a liquid solution or anemulsion.

Exemplary liquid dosage forms include solutions, syrups, liquids,slurries, suspensions, emulsions and the like.

In some embodiments, a liquid dosage form comprises an aqueous carrier.

Aqueous carrier for e.g., solutions or, may contain substances, whichincrease the viscosity of the solution or suspension, such as sodiumcarboxymethyl cellulose, sorbitol or dextran. Optionally, the suspensionmay also contain suitable stabilizers or agents, which increase thesolubility of the conjugates, to allow for the preparation of highlyconcentrated solutions.

In some embodiments, a liquid dosage form comprises an oily, lipophiliccarrier vehicle.

Exemplary lipophilic solvents or vehicles include fatty oils such assesame oil, or synthetic fatty acids esters such as ethyl oleate,triglycerides or liposomes.

In some embodiments, a liquid dosage form comprises a flavoring agent.

In some embodiments, a liquid dosage form comprises one or more of acarrier, a co-solvent, a surfactant, a cyclodextrin, and/or aself-emulsifying drug delivery system, including nanosystems.

According to an aspect of some embodiments of the present invention,there is provided an oral liquid dosage form which comprises any of theconjugates described herein.

In some embodiments, there is provided an oral liquid dosage form whichcomprises a conjugate as described herein, in which the IBD drugcomprises 5-ASA, as described herein.

Any of the compositions and formulations described herein may, ifdesired, be presented in a pack or dispenser device, such as an FDA (theU.S. Food and Drug Administration) approved kit, which may contain oneor more unit dosage forms containing the active ingredient. The packmay, for example, comprise metal or plastic foil, such as, but notlimited to a blister pack or a pressurized container (for inhalation).The pack or dispenser device may be accompanied by instructions foradministration. The pack or dispenser may also be accompanied by anotice associated with the container in a form prescribed by agovernmental agency regulating the manufacture, use or sale ofpharmaceuticals, which notice is reflective of approval by the agency ofthe form of the compositions for human or veterinary administration.Such notice, for example, may be of labeling approved by the U.S. Foodand Drug Administration for prescription drugs or of an approved productinsert. Compositions comprising a compound according to the presentembodiments, formulated in a compatible pharmaceutical carrier may alsobe prepared, placed in an appropriate container, and labeled fortreatment of an IBD, as is detailed hereinabove.

It is expected that during the life of a patent maturing from thisapplication many relevant drugs for treating IBD will be developed andthe scope of the term “a drug suitable for use in the treatment of IBD”is intended to include all such new drugs a priori.

As used herein the term “about” refers to ±10%.

The terms “comprises”, “comprising”, “includes”, “including”, “having”and their conjugates mean “including but not limited to”.

The term “consisting of means “including and limited to”.

The term “consisting essentially of” means that the composition, methodor structure may include additional ingredients, steps and/or parts, butonly if the additional ingredients, steps and/or parts do not materiallyalter the basic and novel characteristics of the claimed composition,method or structure.

The word “exemplary” is used herein to mean “serving as an example,instance or illustration”. Any embodiment described as “exemplary” isnot necessarily to be construed as preferred or advantageous over otherembodiments and/or to exclude the incorporation of features from otherembodiments.

The word “optionally” is used herein to mean “is provided in someembodiments and not provided in other embodiments”. Any particularembodiment of the invention may include a plurality of “optional”features unless such features conflict.

As used herein, the singular form “a”, “an” and “the” include pluralreferences unless the context clearly dictates otherwise. For example,the term “a compound” or “at least one compound” may include a pluralityof compounds, including mixtures thereof.

Throughout this application, various embodiments of this invention maybe presented in a range format. It should be understood that thedescription in range format is merely for convenience and brevity andshould not be construed as an inflexible limitation on the scope of theinvention. Accordingly, the description of a range should be consideredto have specifically disclosed all the possible subranges as well asindividual numerical values within that range. For example, descriptionof a range such as from 1 to 6 should be considered to have specificallydisclosed subranges such as from 1 to 3, from 1 to 4, from 1 to 5, from2 to 4, from 2 to 6, from 3 to 6 etc., as well as individual numberswithin that range, for example, 1, 2, 3, 4, 5, and 6. This appliesregardless of the breadth of the range.

Whenever a numerical range is indicated herein, it is meant to includeany cited numeral (fractional or integral) within the indicated range.The phrases “ranging/ranges between” a first indicate number and asecond indicate number and “ranging/ranges from” a first indicate number“to” a second indicate number are used herein interchangeably and aremeant to include the first and second indicated numbers and all thefractional and integral numerals therebetween.

As used herein the term “method” refers to manners, means, techniquesand procedures for accomplishing a given task including, but not limitedto, those manners, means, techniques and procedures either known to, orreadily developed from known manners, means, techniques and proceduresby practitioners of the chemical, pharmacological, biological,biochemical and medical arts.

As used herein, the term “treating” includes abrogating, substantiallyinhibiting, slowing or reversing the progression of a condition,substantially ameliorating clinical or aesthetical symptoms of acondition or substantially preventing the appearance of clinical oraesthetical symptoms of a condition.

As used herein throughout, the term “alkyl” refers to a saturatedaliphatic hydrocarbon including straight chain and branched chaingroups. Preferably, the alkyl group has 1 to 20 carbon atoms. Whenever anumerical range; e.g., “1-20”, is stated herein, it implies that thegroup, in this case the alkyl group, may contain 1 carbon atom, 2 carbonatoms, 3 carbon atoms, etc., up to and including 20 carbon atoms. Morepreferably, the alkyl is a medium size alkyl having 1 to 10 carbonatoms. The alkyl group may be unsubstituted or substituted, as long asthe substituent does not interfere with the performance and/or intendeduse of the compound. When substituted, the substituent group can be, forexample, cycloalkyl, alkenyl, alkynyl, aryl, heteroaryl,heteroalicyclic, halo, hydroxy, alkoxy, aryloxy, thiohydroxy,thioalkoxy, thioaryloxy, sulfinyl, sulfonyl, cyano, nitro, azide,phosphonyl, phosphinyl, oxo, carbonyl, thiocarbonyl, urea, thiourea,O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl, C-amido,N-amido, C-carboxy, O-carboxy, sulfonamido, and amino, as these termsare defined herein.

A “cycloalkyl” group refers to an all-carbon monocyclic or fused ring(i.e., rings which share an adjacent pair of carbon atoms) group whereinone of more of the rings does not have a completely conjugatedpi-electron system. Examples, without limitation, of cycloalkyl groupsare cyclopropane, cyclobutane, cyclopentane, cyclopentene, cyclohexane,cyclohexadiene, cycloheptane, cycloheptatriene, and adamantane. Acycloalkyl group may be unsubstituted or substituted, as long as thesubstituent does not interfere with the performance and/or intended useof the compound. When substituted, the substituent group can be, forexample, alkyl, alkenyl, alkynyl, aryl, heteroaryl, heteroalicyclic,halo, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy,sulfinyl, sulfonyl, cyano, nitro, azide, phosphonyl, phosphinyl, oxo,carbonyl, thiocarbonyl, urea, thiourea, O-carbamyl, N-carbamyl,O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, C-carboxy, O-carboxy,sulfonamido, and amino, as these terms are defined herein.

An “alkenyl” group refers to an alkyl group which consists of at leasttwo carbon atoms and at least one carbon-carbon double bond.

An “alkynyl” group refers to an alkyl group which consists of at leasttwo carbon atoms and at least one carbon-carbon triple bond.

An “aryl” group refers to an all-carbon monocyclic or fused-ringpolycyclic (i.e., rings which share adjacent pairs of carbon atoms)groups having a completely conjugated pi-electron system. Examples,without limitation, of aryl groups are phenyl, naphthalenyl andanthracenyl. The aryl group may be unsubstituted or substituted, as longas the substituent does not interfere with the performance and/orintended use of the compound. When substituted, the substituent groupcan be, for example, alkyl, alkenyl, alkynyl, cycloalkyl, aryl,heteroaryl, heteroalicyclic, halo, hydroxy, alkoxy, aryloxy,thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl, sulfonyl, cyano, nitro,azide, phosphonyl, phosphinyl, oxo, carbonyl, thiocarbonyl, urea,thiourea, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl,C-amido, N-amido, C-carboxy, O-carboxy, sulfonamido, and amino, as theseterms are defined herein.

A “heteroaryl” group refers to a monocyclic or fused ring (i.e., ringswhich share an adjacent pair of atoms) group having in the ring(s) oneor more atoms, such as, for example, nitrogen, oxygen and sulfur and, inaddition, having a completely conjugated pi-electron system. Examples,without limitation, of heteroaryl groups include pyrrole, furane,thiophene, imidazole, oxazole, thiazole, pyrazole, pyridine, pyrimidine,indole, indolenine, quinoline, isoquinoline and purine. The heteroarylgroup may be unsubstituted or substituted, as long as the substituentdoes not interfere with the performance and/or intended use of thecompound. When substituted, the substituent group can be, for example,alkyl, alkenyl, alkynyl, cycloalkyl, aryl, heteroaryl, heteroalicyclic,halo, hydroxy, alkoxy, aryloxy, thiohydroxy, thioalkoxy, thioaryloxy,sulfinyl, sulfonyl, cyano, nitro, azide, phosphonyl, phosphinyl, oxo,carbonyl, thiocarbonyl, urea, thiourea, O-carbamyl, N-carbamyl,O-thiocarbamyl, N-thiocarbamyl, C-amido, N-amido, C-carboxy, O-carboxy,sulfonamido, and amino, as these terms are defined herein.

A “heteroalicyclic” group refers to a monocyclic or fused ring grouphaving in the ring(s) one or more atoms such as nitrogen, oxygen andsulfur. The rings may also have one or more double bonds. However, therings do not have a completely conjugated pi-electron system. Theheteroalicyclic may be unsubstituted or substituted, as long as thesubstituent does not interfere with the performance and/or intended useof the compound. When substituted, the substituted group can be, forexample, lone pair electrons, alkyl, alkenyl, alkynyl, cycloalkyl, aryl,heteroaryl, heteroalicyclic, halo, hydroxy, alkoxy, aryloxy,thiohydroxy, thioalkoxy, thioaryloxy, sulfinyl, sulfonyl, cyano, nitro,azide, phosphonyl, phosphinyl, oxo, carbonyl, thiocarbonyl, urea,thiourea, O-carbamyl, N-carbamyl, O-thiocarbamyl, N-thiocarbamyl,C-amido, N-amido, C-carboxy, O-carboxy, sulfonamido, and amino, as theseterms are defined herein. Representative examples are piperidine,piperazine, tetrahydrofuran, tetrahydropyran, morpholine and the like.

A “hydroxy” group refers to an —OH group.

An “azide” group refers to a —N═N⁺═N⁻ group.

An “alkoxy” group refers to both an —O-alkyl and an —O-cycloalkyl group,as defined herein.

An “aryloxy” group refers to both an —O-aryl and an —O-heteroaryl group,as defined herein.

A “thiohydroxy” or “thiol” group refers to a —SH group.

A “thioalkoxy” group refers to both an —S-alkyl group, and an—S-cycloalkyl group, as defined herein.

A “thioaryloxy” group refers to both an —S-aryl and an —S-heteroarylgroup, as defined herein.

A “carbonyl” group refers to a —C(═O)—R′ group, where R′ is defined ashereinabove.

A “thiocarbonyl” group refers to a —C(═S)—R′ group, where R′ is asdefined herein.

A “C-carboxy” group refers to a —C(═O)—O—R′ groups, where R′ is asdefined herein.

An “O-carboxy” group refers to an R′C(═O)—O— group, where R′ is asdefined herein.

An “oxo” group refers to a ═O group.

A “carboxylate” or “carboxyl” encompasses both C-carboxy and O-carboxygroups, as defined herein.

A “carboxylic acid” group refers to a C-carboxy group in which R′ ishydrogen.

A “thiocarboxy” or “thiocarboxylate” group refers to both —C(═S)—O—R′and —O—C(═S)R′ groups.

An ester bond refers to a —O—C(═O)— bond.

A “halo” group refers to fluorine, chlorine, bromine or iodine.

A “sulfinyl” group refers to an —S(═O)—R′ group, where R′ is as definedherein.

A “sulfonyl” group refers to an —S(═O)₂—R′ group, where R′ is as definedherein.

A “sulfonate” group refers to an —S(═O)₂—O—R′ group, where R′ is asdefined herein.

A “sulfate” group refers to an —O—S(═O)₂—O—R′ group, where R′ is asdefined as herein.

A “sulfonamide” or “sulfonamido” group encompasses both S-sulfonamidoand N-sulfonamido groups, as defined herein.

An “S-sulfonamido” group refers to a —S(═O)₂—NR′R″ group, with each ofR′ and R″ as defined herein.

An “N-sulfonamido” group refers to an R′S(═O)₂—NR″ group, where each ofR′ and R″ is as defined herein.

An “O-carbamyl” group refers to an —OC(═O)—NR′R″ group, where each of R′and R″ is as defined herein.

An “N-carbamyl” group refers to an R′OC(═O)—NR″— group, where each of R′and R″ is as defined herein.

A “carbamyl” or “carbamate” group encompasses O-carbamyl and N-carbamylgroups.

A carbamate bond describes a —O—C(═O)—NR′— bond, where R′ is asdescribed herein.

An “O-thiocarbamyl” group refers to an —OC(═S)—NR′R″ group, where eachof R′ and R″ is as defined herein.

An “N-thiocarbamyl” group refers to an R′OC(═S)NR″— group, where each ofR′ and R″ is as defined herein.

A “thiocarbamyl” or “thiocarbamate” group encompasses O-thiocarbamyl andN-thiocarbamyl groups.

A thiocarbamate bond describes a —O—C(═S)—NR′— bond, where R′ is asdescribed herein.

A “C-amido” group refers to a —C(═O)—NR′R″ group, where each of R′ andR″ is as defined herein.

An “N-amido” group refers to an R′C(═O)—NR″— group, where each of R′ andR″ is as defined herein.

An “amide” group encompasses both C-amido and N-amido groups.

An amide bond describes a —NR′—C(═O)— bond, where R′ is as definedherein.

A “urea” group refers to an —N(R′)—C(═O)—NR″R′″ group, where each of R′and R″ is as defined herein, and R′″ is defined as R′ and R″ are definedherein.

A “nitro” group refers to an —NO₂ group.

A “cyano” group refers to a —C≡N group.

The term “phosphonyl” or “phosphonate” describes a —P(═O)(OR′)(OR″)group, with R′ and R″ as defined hereinabove.

The term “phosphate” describes an —O—P(═O)(OR′)(OR″) group, with each ofR′ and R″ as defined hereinabove.

A “phosphoric acid” is a phosphate group is which each of R is hydrogen.

The term “phosphinyl” describes a —PR′R″ group, with each of R′ and R″as defined hereinabove.

The term “thiourea” describes a —N(R′)—C(═S)—NR″— group, with each of R′and R″ as defined hereinabove.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination or as suitable in any other describedembodiment of the invention. Certain features described in the contextof various embodiments are not to be considered essential features ofthose embodiments, unless the embodiment is inoperative without thoseelements.

Various embodiments and aspects of the present invention as delineatedhereinabove and as claimed in the claims section below find experimentalsupport in the following examples.

EXAMPLES

Reference is now made to the following examples, which together with theabove descriptions illustrate some embodiments of the invention in a nonlimiting fashion.

Example 1 Chemical Syntheses

General Procedure:

The PL-drug conjugates disclosed herein are prepared according topublished procedures (see, for example, Dvir et al., 2008 and Kurz andScriba, 2000).

In an exemplary general procedure, a lysophospholipid, the (IBD) drug ofinterest and, optionally, a suitable starting material for providing thelinker of interest (the bridging moiety), are used as startingmaterials.

The term “lysophospholipid” as used herein encompasses a derivative ofphosphatidic acid in which one of the fatty acid chains has beenremoved, leaving at the corresponding position a hydroxyl group.

The term “phosphatidic acid”, as known in the art, is used tocollectively represent fatty acid derivatives of glycerophosphates,which are composed of a glycerol backbone to which 1 mole of phosphoricacid is attached via an ester bond at the terminal 3-hydroxyl group(position sn-3) and 2 moles of fatty acids are attached via an esterbond at the other two hydroxyl groups (at positions sn-1 and sn-2).Conjugation of the fatty acids to the glycerolic backbone results infatty acyl moieties at positions sn-1 and sn-2.

A “phosphatidic acid” can be represented as follows:

wherein:

A₁ and A₂ are each independently a saturated or unsaturated hydrocarbonchain being at least 3 carbon atoms in length, as defined herein; and

to Ra and Rb are each independently hydrogen, alkyl, cycloalkyl, aryl,aminoalkyl, hydroxyalkyl, and the like, or are selected such that thegroup —P(═O)(ORa)(ORb) represents a phosphoryl choline, phosphorylethanolamine, phosphoryl serine, phosphoryl cardiolipin, phosphorylinositol, ethylphosphocholine, phosphorylmethanol, phosphorylethanol,phosphorylpropanol, phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phosphoglycerol.

Phosphatidic acids that comprise some of the above-indicated phosphorylgroups can be referred to, for example, as phosphatidyl choline,phosphatidyl ethanolamine, phosphatidyl serine, phosphatidylcardiolipin, phosphatidyl inositol, phosphatidyl ethyl phosphocholine,phosphatidyl methanol, phosphatidyl ethanol, phosphatidyl propanol,phosphatidyl butanol, phosphatidyl ethanolamine-N-lactose, phosphatidylethanolamine-N-[methoxy(propylene glycol)], phosphatidylinositol-4-phosphate, phosphatidyl inositol-4,5-biposphonate,phosphatydil ethanolamine-diethylenetriamine-pentaacetate, anddinitrophenyl-phosphatidyl ethanolamine.

Exemplary lysophospholipids include derivatives of any of theabove-described phosphatidic acids, in which the ester bond at positionsn-1 or sn-2 has been cleaved into a free fatty acid and a hydroxy groupat the respective position of the glycerol backbone.

Lysophospholipids having a hydroxyl group at position sn-1 can berepresented by:

wherein A₂, Ra and Rb are as defined herein.

Lysophospholipids having a hydroxyl group at position sn-2 can berepresented by:

wherein A₁, Ra and Rb are as defined herein.

Lysophospholipids having a hydroxyl group at position sn-2, as describedherein, are preferred. Such lysophopholipids are also referred to as1-acyl-2-lyso-phosphoglycerol. An exemplary lysophospholipid islysolecithin (derived from phosphatidyl choline).

The drug of interest includes any of the drugs suitable for thetreatment of an IBD, as described herein, including, for example, 5-ASA,tacrolimus and methotrexate.

The linker of interest can be any of the bridging moieties (or linkingmoieties) as described herein.

A suitable starting material (precursor) for providing the linker ofinterest is preferably a bi-functional compound having at one end afirst reactive group for forming a bond with the hydroxyl group of thelysophospholipid, and at another end a second reactive group for forminga bond with the drug of interest.

As used herein, the phrase “reactive group”, which refers to both thefirst and the second reactive groups, describes a chemical moiety thatis capable of undergoing a chemical reaction that typically leads to abond formation. The bond, according to some embodiments of the presentinvention, is preferably a covalent bond. Chemical reactions that leadto a bond formation include, for example, nucleophilic and electrophilicsubstitutions, nucleophilic and electrophilic addition reactions,cycloaddition reactions, rearrangement reactions and any other knownorganic reactions that involve a reactive group.

Representative examples of suitable reactive groups according to someembodiments of the present invention include, without limitation, amine,halide, acyl-halide, sulfonate, sulfoxides, hydroxy, alkoxy, aryloxy,thiohydroxy, thioalkoxy, thioaryloxy, cyano, nitro, azo, isocyanate,sulfonamide, carboxylate, thiocarbamate, urea, thiourea, carbamate,amide, guanyl, guanidine and hydrazine, as these terms are definedhereinabove.

In some embodiments, the first and/or second reactive group(s) include,but are not limited to, halide, amine, carboxylate, thiol, alkoxy,aryloxy, thioalkoxy, thioaryloxy, acyl-halide, and anhydride.

In some embodiments, the first reactive group is selected so as to forman ester bond with the hydroxyl group of the lysophospholipid. Such anester bond is cleavable by PLA₂. Suitable first reactive groupstherefore include, but are not limited to, carboxylates, acyl halidesand anhydrides.

In some embodiments, the second reactive group is selected so as to forma bond with the drug of interest and hence is selected so as to form abond with a functional group of the drug. In some embodiments, the bondis stable (non-cleavable) under physiological conditions. Exemplarybonds include, without limitation, ester bond, amide bond and thioesterbond. Thus, for example, in cases where the drug of interest has afunctional group such as amine, thiol or hydroxyl, the second reactivegroup can be a carboxylate, an anhydride or an acyl halide. In caseswhere the drug of interest has a functional group such as a carboxylate,the second reactive group can be amine, thiol or hydroxyl. Any “couples”of a second reactive group of the precursor of the bridging moiety and afunctional group on the drug of interest, which are compatible one withanother by means of forming a bond therebetween, are contemplated.

In an exemplary procedure, where the drug is conjugated directly to thelysophospholipid, the drug of interest preferably comprises acarboxylate (e.g., a carboxylic acid) or, alternatively, is modified soas to comprise a carboxylate. The carboxylate can further be modified toa more reactive group, such as an acyl halide. In some embodiments,prior to being reacted with the lysophospholipid, the carboxylate groupon the drug is converted to an acyl chloride or an anhydride, so as tofalicitate the reaction. In some embodiments, the reaction is performedin the presence of a coupling agent suitable for esterification (e.g.,DCC).

In another exemplary procedure, where the drug is conjugated to thelysophospholipid via a liker, a bifunctional compound selected forproviding the linker of interest is reacted with a suitable protectinggroup, so as to have the second reactive group protected, and theprotected compound is reacted with the lysophospholipid. In someembodiment, the protected compound is converted to an anhydride prior tothe reaction. Upon the reaction, a protected moiety of the compound isconjugated to the lysophospholipid, and this intermediate is furtherreacted with the drug by (i) removing the protecting group, so as togenerate the second reactive group; and (ii) reacting with the drug ofinterest so as to form the desired bond, as described hereinabove.

In any of the above-described general procedures, the chemical structureof obtained product is verified using common analytical procedures(e.g., NMR measurements, such ¹H, ¹³C and ³¹P NMR spectra, elementalanalysis, IR spectroscopy, mass spectrometry and/or UV spectrometry. Thepurity of the product is determined by high-performance liquidchromatography and/or thin layer chromatography.

If required, purification of the obtained product is performed by commonprocedures such as, for example, column chromatography,recrystallization, and the like.

Preparation of a Conjugate of 5-ASA and Lysolecithin (Having a 5-CarbonLinker)

A conjugate of 5-ASA and lysolecithin, having the following structure:

2-(5-(5-amino-2-hydroxybenzamido)pentanoyloxy)-3-(palmitoyloxy)propyl2-(trimethylammonio)ethyl phosphate

was prepared according to Scheme 1 below.

Preparation of Compound 1

To a solution of Lysophosphatidyl choline (100 mg, 0.2 mmol) andFmoc-N-aminohexanoic acid (83 mg, 0.24 mmol) inchloroform/dichloromethane 1:4 v/v (5 ml) were added DMAP (5 mg, 0.041mmol) and DCC (37.08 mg, 0.18 mmol). The mixture was stirred at roomtemperature for 2 hours. The extract was successively washed with 0.1NHCl, saturated NaHCO₃ and water and the solvents were thereafter removedunder reduced pressure.

Preparation of Compound 2

The Fmoc group was removed using 25% piperidine in DMF (6 minutes).Compound 2 was obtained after crystallization with methanol:water (4:1v/v) and re-crystallization with acetone.

Preparation of Compound 3

Compound 3 was prepared by mixing Compound 2 (200 mg, 1.52 mmol) and5-ASA (302.59 mg, 1.97 mmol) with DCC (344.98 mg, 1.67 mmol) in THF at0° C. and stirring the obtained mixture for 1 hour at 0° C., followingby stiffing at room temperature for 2 hours. The obtained DCUprecipitate was removed at the end of the procedure using methanol:water(4:1 v/v).

The product structure is verified as described hereinabove.

Preparation of a Series of PL-5-ASA Conjugates

Following the above-described procedures, a series of conjugates of5-ASA and various lysophopholipids is prepared. For eachlysophopsholipid utilized, the 5-ASA is attached in the absence of alinker and in presence of various linkers, as described herein.

The disclosed series of PL-5-ASA conjugates is then utilized in variousactivity studies, for identifying the most potent conjugate for anindicated condition.

Example 2 Degradation by PLA₂

PLA₂ belongs to a family of enzymes that catalyze the hydrolysis of thesn-2 fatty acyl bond of phospholipids to liberate free fatty acid andlysophospholipid (Kudo and Murakami 2002).

Cleavage of the phospholipid drug conjugates as described herein, in thepresence of a PLA₂ from is determined as follows:

A mixture of solutions of a phospholipid-drug conjugate (e.g., aPL-5-ASA conjugate as described herein) in ethanol,L-α-phosphatidylcholine and di-o-hexadecyl in Chloroform:MeOH (1:1 v/v),and of phosphatidyl choline (in Chloroform:MeOH 1:1), are evaporatedunder a stream of nitrogen. Reaction buffer (e.g., containing 300 mMNaCl, 10 mM CaCl₂, 25 mM Tris-HCl pH 7.4) is added, and the lipidmixture is sonicated for 10 minutes in a sonication bath, transferred toice for a few minutes, sonicated for additional 10 minutes, andtransferred again to ice.

PLA₂ is thereafter added to the tubes, and the obtained solutions areincubated for 1.5 hours at 25° C.

Two types of controls are used: reaction mixture without PLA₂; and areaction mixture that contains PLA₂ but do not contain lipids.

Example 3 Intestinal Permeability

The intestinal permeability of the conjugates is assessed to ensure thatthe intact PL-5-ASA conjugate is not absorbed. The intestinalpermeability is evaluated using transepithelial permeability studiesacross Caco-2 cell monolayers, as previously described [see, forexample, Dahan et al., Am. J. Physiol. Gastrointest. Liver Physiol.2009].

Briefly, 5×10⁴ cells/cm² are seeded onto collagen-coated membranes(12-well Transwell plate, 0.4-μm pore size, 12-mm diameter; CorningCostar, Cambridge, Mass.) and are allowed to grow for 21 days. Mannitoland Lucifer yellow permeabilities are assayed for each batch of Caco-2monolayers (n=3), and transepithelial electrical resistance (TEER)measurements are performed on all monolayers (Millicell-ERS epithelialVoltohmmeter; Millipore, Bedford, Mass.). Monolayers with apparentmannitol and Lucifer yellow permeability <3×10⁷ cm/s and TEERvalues >300 Ωcm2 are used for all studies. On the experiment day, themonolayers are rinsed and incubated for 20 minutes with a blanktransport buffer. The transport buffer contains 1 mM CaCl₂, 0.5 mMMgCl₂.6H₂O, 145 mM NaCl, 3 mM KCl, 1 mM NaH₂PO₄, 5 mM D-glucose, and 5mM MES. Similar pH is used in both apical (AP) and basolateral (BL)sides (pH 6.5) to maintain constant degree of ionization in both AP-BLand BL-AP direction experiments and to avoid possible influence of thisfactor on the permeability across the cells.

Following the 20-minutes incubation, the drug-free transport buffer isremoved from the donor side (AP in the AP-BL-direction studies or BL inthe BL-AP-direction studies) and replaced by a drug uptake buffersolution (pH 6.5), with or without the tested conjugate. Throughout theexperiment, the transport plates are kept in a shaking incubator (50revolution/minute) at 37° C. Samples are taken from the receiver side atvarious time points up to 120 minutes (100 μl from BL side or 70 μl fromAP side), and similar volumes of blank buffer are added following eachsample withdrawal. At the last time point (120 minutes), a sample istaken from the donor side as well to confirm mass balance. Samples areimmediately assayed for conjugate content. All Caco-2 monolayers arechecked for confluence by measuring the TEER before and after thetransport study (TEER values remained steady throughout the experiment).

The intestinal permeability is further evaluated by measuring in-situintestinal perfusions in a rat model, as previously described [see, forexample, Dahan et al., European Journal of Pharmaceutical Sciences.36:320-329 (2009), which is incorporated by reference as if fully setforth herein.

Briefly, rats are anesthetized with an intra-muscular injection of 1ml/kg of ketamine-xylazine solution (9%:1%, respectively) and placed ona heated surface maintained at 37° C. (Harvard Apparatus Inc.,Holliston, Mass.). The abdomen is opened by amidline incision of 3-4 cm.A proximal jejunal (13.5±1.6 cm average distance of the inlet from thepylorus) or distal ileal segment (14.7±1.8 cm average distance of theinlet from the cecum) of approximately 10 cm is carefully exposed andcannulated on two ends with flexible PVC tubing (2.29 mm i.d., inlettube 40 cm, outlet tube 20 cm, Fisher Scientific Inc., Pittsburgh, Pa.).Care is taken to avoid disturbance of the circulatory system, and theexposed segment is kept moist with 37° C. normal saline solution. Theperfusate is incubated in a 37° C. water bath to maintain temperature,and a perfusion solution containing 10m MMES buffer, pH 6.5, 135 mMNaCl, 5 mM KCl, and 0.1 mg/ml phenol red with an osmolarity of 290mosm/l is pumped through the intestinal segment (Watson MarlowPumps323S, Watson-MarlowBredel Inc., Wilmington, Mass.). The isolated segmentis rinsed with blank perfusion buffer, pH 6.5 at a flow rate of 0.5ml/min in order to clean out any residual debris.

At the start of the study, perfusion solution containing the testedconjugate is perfused through the intestinal segment at a flow rate of0.2 ml/min Phenol red is added to the perfusion buffer as anonabsorbable marker for measuring water flux.

The concentrations of the conjugates used in the perfusion studies aredetermined by dividing the highest prescribed dose by 250 ml, thestandard volume for a glass of water advised to be taken with the doseand hence the accepted minimal gastric volume, in order to represent themaximal drug concentration present in the intestinal segment, and werewithin their intrinsic solubility reported at pH 6.5 (Avdeef and Berger,2001; Avdeef et al., 2000). The perfusion buffer is first perfused for 1hour, in order to assure steady state conditions (as also assessed bythe inlet over outlet concentration ratio of phenol red which approaches1 at steady state). Following reaching to steady state, samples aretaken in 10 minutes intervals for 1 hour (10, 20, 30, 40, 50, and 60min). All samples including perfusion samples at different time points,original drug solution, and inlet solution taken at the exit of thesyringe are immediately assayed by HPLC. Following the termination ofthe experiment, the length of the perfused intestinal segment isaccurately measured.

Example 4 In vivo Studies

PL-5-ASA conjugates which exhibit high activation by PLA₂ and lowintestinal permeability as an intact conjugate are selected for in vivostudies.

In vivo studies are performed in IBD (UC and CD) models in rats.

Any available IBD rat model can be used. In an exemplary model, mice arelightly anesthetized with halothane, and a 3.5 F catheter is insertedintrarectally 4 cm from the anus. To induce colitis, 100 μL of 3 mg TNBS(Sigma Chemical Co, St. Louis, Mo.) in 50% ethanol (to break theintestinal epithelial barrier) are slowly administered into the lumenvia the catheter filled to a 1-mL syringe. Control mice receive 50%ethanol alone (100 μL).

Quantification of PLA₂ is performed by Western blotting with amonoclonal antibody against PLA₂, as described in, for example, Dahan etal., Drug Metab Dispos., 2009; or otherwise by quantification of PLA2gene expression, protein content and enzymatic activity, as described,for example, in Haapamaki et al. (1999a), in Lilja et al. (1995) and/orin Minami et al. (1994), all of which are incorporated by reference asif fully set forth herein.

Pharmacokinetic evaluation of the conjugates activity in the rat modelis performed as described, for example, in Dahan and Hoffman 2005, andDahan and Hoffman 2006, which are incorporated by reference as if fullyset forth herein. Pharmacodynamic studies are performed by the SSD ratmodel for IBD.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims.

All publications, patents and patent applications mentioned in thisspecification are herein incorporated in their entirety by referenceinto the specification, to the same extent as if each individualpublication, patent or patent application was specifically andindividually indicated to be incorporated herein by reference. Inaddition, citation or identification of any reference in thisapplication shall not be construed as an admission that such referenceis available as prior art to the present invention. To the extent thatsection headings are used, they should not be construed as necessarilylimiting.

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1-33. (canceled)
 34. A method of treating an inflammatory bowel diseasein a subject in need thereof, the method comprising orally administeringto the subject a therapeutically effective amount of a conjugate whichcomprises a drug useful in the treatment of the inflammatory boweldisease covalently linked to a phospholipid.
 35. The method of claim 34,wherein the conjugate is formulated as a liquid oral formulation. 36.The method of claim 34, wherein said drug useful in the treatment ofinflammatory bowel disease is selected from the group consisting of adrug that comprises 5-ASA, tacrolimus and methotrexate.
 37. The methodof claim 34, wherein said phospholipid is a phosphoglycerol.
 38. Themethod of claim 37, wherein said drug is linked to position sn-2 of saidphosphoglycerol.
 39. The method of claim 34, wherein said drug is linkedto said phospholipid directly.
 40. The method of claim 34, wherein saiddrug is linked to said phospholipid via a bridging unit.
 41. The methodof claim 40, wherein said bridging unit comprises an alkylene being from1 to 20 carbon atoms in length.
 42. The method of claim 40, wherein saidalkylene is being from 3 to 6 carbon atoms in length.
 43. The method ofclaim 34, wherein said conjugate has a general Formula:

wherein: A is an alkylene chain being 3-30 carbon atoms in length; X issaid bridging unit or absent; D is said drug suitable for use in thetreatment of said inflammatory bowel disease; and R is selected from thegroup consisting of —P(═O)(ORa)(ORb), phosphoryl choline, phosphorylethanolamine, phosphoryl serine, phosphoryl cardiolipin, phosphorylinositol, ethylphosphocholine, phosphorylmethanol, phosphorylethanol,phosphorylpropanol, phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.
 44. The method of claim 43, wherein saiddrug comprises 5-ASA.
 45. The method of claim 44, wherein X is analkylene chain being 3-6 carbon atoms in length.
 46. The method of claim44, wherein R is phosphoryl choline.
 47. The method of claim 44, whereinA is an alkylene chain being 15 or 17 carbon atoms in length.
 48. Apharmaceutical composition comprising, as an active ingredient, aconjugate which comprises a drug useful in the treatment of theinflammatory bowel disease covalently linked to a phospholipid, and apharmaceutically acceptable carrier, the composition being formulatedfor oral administration and is being packaged in a packaging materialand identified in print, in or on said packaging material, for use inthe treatment of said inflammatory bowel disease.
 49. The composition ofclaim 48, being formulated as a liquid oral formulation.
 50. Thecomposition of claim 49, wherein said drug useful in the treatment ofinflammatory bowel disease is selected from the group consisting of adrug that comprises 5-ASA, tacrolimus and methotrexate.
 51. Thecomposition of claim 49, wherein said phospholipid is a phosphoglycerol.52. The composition of claim 51, wherein said drug is linked to positionsn-2 of said phosphoglycerol.
 53. The composition of claim 49, whereinsaid drug is linked to said phospholipid directly.
 54. The compositionof claim 49, wherein said drug is linked to said phospholipid via abridging unit.
 55. The composition of claim 54, wherein said bridgingunit comprises an alkylene being from 1 to 20 carbon atoms in length.56. The composition of claim 54, wherein said alkylene is being from 3to 6 carbon atoms in length.
 57. The composition of claim 49, whereinsaid conjugate has a general Formula:

wherein: A is an alkylene chain being 3-30 carbon atoms in length; X issaid bridging unit or absent; D is said drug suitable for use in thetreatment of said inflammatory bowel disease; and R is selected from thegroup consisting of —P(═O)(ORa)(ORb), phosphoryl choline, phosphorylethanolamine, phosphoryl serine, phosphoryl cardiolipin, phosphorylinositol, ethylphosphocholine, phosphorylmethanol, phosphorylethanol,phosphorylpropanol, phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.
 58. The composition of claim 57, whereinsaid drug comprises 5-ASA.
 59. The composition of claim 58, wherein X isan alkylene chain being 3-6 carbon atoms in length.
 60. The compositionof claim 58, wherein R is phosphoryl choline.
 61. The composition ofclaim 58, wherein A is an alkylene chain being 15 or 17 carbon atoms inlength.
 62. An oral liquid dosage form comprising a conjugate whichcomprises a drug useful in the treatment of the inflammatory boweldisease covalently linked to a phospholipid, and a pharmaceuticallyacceptable carrier.
 63. The dosage form of claim 62, wherein said druguseful in the treatment of inflammatory bowel disease is selected fromthe group consisting of a drug that comprises 5-ASA, tacrolimus andmethotrexate.
 64. The dosage form of claim 62, wherein said phospholipidis a phosphoglycerol.
 65. The dosage form of claim 64, wherein said drugis linked to position sn-2 of said phosphoglycerol.
 66. The dosage formof claim 62, wherein said conjugate has a general Formula:

wherein: A is an alkylene chain being 3-30 carbon atoms in length; X issaid bridging unit or absent; D is said drug suitable for use in thetreatment of said inflammatory bowel disease; and R is selected from thegroup consisting of —P(═O)(ORa)(ORb), phosphoryl choline, phosphorylethanolamine, phosphoryl serine, phosphoryl cardiolipin, phosphorylinositol, ethylphosphocholine, phosphorylmethanol, phosphorylethanol,phosphorylpropanol, phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.
 67. The dosage form of claim 66, whereinsaid drug comprises 5-ASA.
 68. The dosage form of claim 67, wherein X isan alkylene chain being 3-6 carbon atoms in length.
 69. The dosage formof claim 67, wherein R is phosphoryl choline.
 70. The dosage form ofclaim 67, wherein A is an alkylene chain being 15 or 17 carbon atoms inlength.
 71. A process of preparing a conjugate which comprises aphospholipid having attached thereto a drug suitable for the treatmentof an inflammatory bowel disease, the process comprising covalentlycoupling said drug to a lysophospholipid.
 72. A conjugate comprising aphospholipid having attached thereto 5-amino salicylic acid (5-ASA). 73.The conjugate of claim 72, wherein said conjugate has a general Formula:

wherein: A is an alkylene chain being 3-30 carbon atoms in length; X isa bridging unit or absent; D is 5-ASA; and R is selected from the groupconsisting of —P(═O)(ORa)(ORb), phosphoryl choline, phosphorylethanolamine, phosphoryl serine, phosphoryl cardiolipin, phosphorylinositol, ethylphosphocholine, phosphorylmethanol, phosphorylethanol,phosphorylpropanol, phosphorylbutanol, phosphorylethanolamine-N-lactose,phosphoethanolamine-N-[methoxy(propylene glycol)],phosphoinositol-4-phosphate, phosphoinositol-4,5-biposphonate,pyrophosphate, phosphoethanolamine-diethylenetriamine-pentaacetate,dinitrophenyl-phosphoethanolamine and phsophoglycerol, wherein Ra and Rbare each independently selected from the group consisting of hydrogen,alkyl, cycloalkyl and aryl.
 74. An oral liquid dosage form comprisingthe conjugate of claim 72.